Should You Worry? Petrol in a Diesel Car in Flexbury
Likely less than you are now — provided nobody has started the vehicle. Everyone around Flexbury starts with "have I ruined it?", and the fair answer is usually no: petrol left in that tank of any diesel stays harmless until priming, cranking or driving draws it into the fuel system. Keep it like that: leave your engine off and call Petrol in Diesel. The rest of this page sets out what petrol actually does to a diesel, how to judge how far it has got, and how to make sure it does not happen to you again.
What petrol in a diesel does to your engine
Passing through a motor, diesel does two things at the same time. Lubricating comes before burning; it does both. Built to very fine clearances, the injectors and your pump depend on your diesel moving through them to stop their surfaces wearing against one another.
Petrol does the first task badly and the second not at all. Being less viscous than diesel, petrol strips away the protection a fuel system needs, leaving a pump running on the blend wearing itself. It's equally made to resist igniting under compression — the opposite of what a diesel needs — which is why you get the rattling.
Together, those make the shape of the problem clear. It's circulation that does the harm, not contact. Petrol in a tank is a fuel issue. Once the pump has been labouring on that petrol, a mechanical problem has started: anything shed by a pump that's grinding travels onward to the fuel injectors with your fuel.
How bad is petrol in a diesel? Four scenarios our technicians see around Flexbury
The best case there is: filled up, never started. Just that tank has petrol in it, so the task is emptying the tank and purging the fuel system where the car stands. This scenario can only truly take place on a forecourt: anywhere else, your car got there by being driven.
A moment's running, or just the ignition on. The system has been primed, and so petrol has left the tank and reached the filter and the fuel lines. Still normally simple: drain, flush, and the fuel filter sorted.
Driven a couple of miles. Now your pump has spent those miles labouring on weakened fuel. The work is that tank, the lines, the fuel filter and clean fuel through the entire circuit, and how hard your car was driven counts as much as how far. Driving the children to Bude Primary Academy - Infants is one sort of trip. Very different a second time: a trip to Plymouth, under 50 miles away, or some mileage on the M5, under 50 miles from Flexbury, where the engine kept labouring hard.
It protested, and only then stopped: smoke, knocking, a throttle gone soft, an idle gone lumpy. That's the motor telling you its fuel no longer is acting like diesel. Whether it is the verge on Cedar Grove, a lay-by or a side street, stop where you are then leave it. The drain and flush-through still go first, and they sort it out: if a vehicle is stopped quickly, lasting damage is very uncommon.
Flexbury drivers and that petrol in a diesel myths they hear
It will not be fine. The myth: "Fill it the rest of the way with diesel and it will be." Nothing comes out when you top up — the tank simply holds more of the same blend. Percentage isn't how a diesel fuel system copes with petrol, however much that advice assumes.
"Current diesels can handle a little petrol" — a myth, and nearer the opposite. At higher pressure, through finer components: that is how a modern diesel moves its fuel, so the lubrication counts for more, not less.
The myth that catches motorists off guard: if it starts and drives, it must be unharmed. The motorist of a petrol engine fed diesel usually has no choice but to stop, because it will not run, and the damage stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump grinds. Fine and running aren't the same thing.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a different issue. That petrol is still in the tank afterwards, and whatever it has thinned isn't put back.
The next start draws petrol back round your pump out of your lines and the filter, where some of that sits after the engine has been run. That is why draining the tank yourself does not sort it — a myth. Besides, petrol cleared into a can by the road is truly hazardous.
How petrol ends up: petrol in a diesel
It is rarely carelessness, and no one does it on purpose. A diesel nozzle mostly won't go into a petrol motor, yet the slimmer petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one mistake easy, and only in one direction.
Routine and your car falling out of step is when it takes place. A new motor, a hire car or a courtesy car. Households running one of each, petrol and diesel. The pumps in a different order on a well-known forecourt. Racing for a train at the nearest station and fuelling up en route. Precisely the moment it happens: after years of driving petrol, a driver fills a diesel Skoda Octavia for the first time. The hand does what it has always done once you add rain, a phone call or a back seat full of kids.
How to prevent petrol in a diesel at your next fill-up around Flexbury
- A green handle for unleaded and black for diesel is normal in the UK — yet not on each forecourt. Trust the label on the pump, not the colour.
- Many cars state the fuel inside the filler flap or on the cap, so check it on your first fill in any motor you don't know.
- Label your key. In a house with one of each, a coloured fob or a sticker on the diesel's key does more than any amount of meaning to remember.
- It sounds silly and it does the trick: on your first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump.
- Tuck the phone away. This is an easy mistake to make while you are thinking about something else.
- Some diesels come with a filler designed to block a petrol nozzle, and devices you can add are available for cars without one. Such an inhibitor helps up to a point — as a backstop, not a reason to stop checking the petrol pump.
- Spotting it mid-fill? Stop there and then. A thinner mix follows from less petrol inside that tank, yet the next stage stays the same: do not fire it up.
Petrol already in a diesel in Flexbury? Start here
Then the order of things is brief. Don't turn your ignition on, and don't start it. Ask the attendants to help you push it away from the pump if you're still at the forecourt, whether that's Shell or somewhere else. What was put in, about how much, and whether it's run: tell us that when you call 0333 366 0103.
If it was AdBlue rather than petrol, say so. That's a separate problem — corrosion and deposits rather than lost lubrication — and it has its own page for Flexbury.
Why one petrol in a diesel task around Flexbury costs more than another
Four separate tasks lie behind the four scenarios above — which is why there is no honest single price. The situation itself does most of the work of moving the cost. Two things follow that: the petrol that went in as a share of what that tank holds, then the place your car is in and whether a technician can get to it safely.
What was put in, how much, and if it's run — three queries our engineers ask before pricing, not after, for exactly that reason. Those replies are what change a range into one firm number.
About Flexbury
Flexbury is a coastal suburban area in Cornwall, situated near the popular seaside resort of Bude. Flexbury sits at a low elevation of around 16 metres, overlooking the Atlantic coastline and surrounded by nearby places like Crooklets and Poughill. Flexbury has a population of approximately 2614 people, predominantly living in detached housing. Flexbury is located within commuting distance of Plymouth, which is around 36 miles away.
Across Cornwall and around Flexbury: fuel drain cover
Bude, Crooklets and Poughill are among the places around Flexbury that the same teams work, answering petrol in diesel calls across Flexbury's EX postcode area. No need to bring your vehicle to us. Forecourts, supermarket car parks, lay-bys and your own driveway are all places where we work.
In Flexbury and still at the petrol pump?
In that case, you could not be in a better position. Leave it switched off, then ring.